Play midi files via external midi devices or soft synth.
Playmidi is a web and curses and SDL-based MIDI file player for Linux and MacOS and Chrome (via Web MIDI and Web Audio apis). All recent development has moved to https://github.com/nlaredo/playmidi
It supports software rendering of midi files via SDL audio and can also output midi events to external midi devices (in time with SDL audio soft synth) via both alsa sequencer api (linux) and coremidi api (osx).
Whale Music Server is (or rather WILL be) a music player similar to MPD. Program is in very early development stage, so please, dont waste your time on it. ;)
The 'Streamers Webplayer' is an 'open source' web-based playback tool for 'Nullsoft's SHOUTcast server '. It offers the user and administrator, a very simple and clear user interface, to receive SHOUTcast's stream.
JACo MP3 Player is a cross platform java mp3 player. Features: very low CPU usage (~2%), incredible small library (~90KB), doesn't need JMF, easy to integrate in any application, easy to integrate in any web page (as applet).